The following Background includes information that may be useful in understanding the present inventions. It is provided as an aid to understanding the utility of the invention and background information that is incorporated by reference to the extent needed to practice the invention. Information provided in this Background section may form part of the present invention and its presence in this section is not an admission that the information is prior art to the claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.
Hydrogen is an important feedstock for the manufacture of chemicals and as a clean fuel in combustion engines and in fuel cells (Garcia et al. 2000). It finds uses in activities such as the manufacture of fertilizers, petroleum processing, methanol synthesis, annealing of metals and producing electronic materials. In the foreseeable future emergence of fuel cell technology will extend the use of hydrogen to domestic and vehicle applications. The primary synthetic routes for the production of hydrogen have consisted of catalytic steam reforming of methane, C2-C4, natural gas, LPG (liquefied petroleum gas), naphtha or other light hydrocarbons. Other routes have reportedly used the partial oxidation of heavy oil residues and coal gasification from these starting materials. Increased interest in fuel hydrogen production requires the development of economically and environmentally sustainable processes that compete with processes involving derivation of hydrogen gas from hydrocarbons obtained from petrochemical and natural gas sources. The world's supply of petroleum is being depleted at an increasing rate. Eventually, demand for petrochemical derived products will outstrip the supply of available petroleum. When this occurs, the market price of petroleum and, consequently, petroleum derived products will likely increase, making products derived from petroleum more expensive and less desirable. As the available supply of petroleum decreases, alternative sources and, in particular, renewable sources of comparable products will necessarily have to be developed. One potential renewable source of petroleum derived products is products derived from bio-based matter, such as agricultural and forestry products. Use of bio-based products may potentially counteract, at least in part, the problems associated with depletion of the petroleum supply.
In an effort to diminish dependence on petroleum products the United States government enacted the Farm Security and Rural Investment Act of 2002, section 9002 (7 U.S.C. 8102), hereinafter “FRISA”, which requires federal agencies to purchase bio-based products for all items costing over $10,000. In response, the United States Department of Agriculture (“USDA”) has developed Guidelines for Designating Bio-based Products for Federal Procurement (7 C.F.R. §2902) to implement FRISA, including the labeling of bio-based products with a “U.S.D.A. Certified Bio-based Product” label.
Biology offers an attractive alternative for industrial manufacturers looking to reduce or replace their reliance on petrochemicals and petroleum derived products. The replacement of petrochemicals and petroleum derived products with products and/or feed stocks derived from biological sources (i.e., bio-based products) offer many advantages. For example, products and feed stocks from biological sources are typically a renewable resource. As the supply of easily extracted petrochemicals continue to be depleted, the economics of petrochemical production will likely force the cost of the petrochemicals and petroleum derived products to higher prices compared to bio-based products. In addition, companies may benefit from the marketing advantages associated with bio-derived products from renewable resources in the view of a public becoming more concerned with the supply of petrochemicals.
Renewable lignocellulosic biomass feedstocks represent alternative feedstocks for the production of hydrogen. Recent developments in this area have reported the use of renewable carbohydrate feedstocks that are derived from dilute sugar streams and lignocellulosics (i.e. soft and hardwoods, crop residues such as straws, hulls, and/or fibers) to produce hydrogen using thermochemical processes such as pyrolysis and/or gasification. It has been reported by Cortright, et al., U.S. Pat. No. 6,699,457, that a substantial amount of hydrogen production is performed by steam reforming of hydrocarbons according to the formula:CxH2x+2+xH2O→xCO+(2x+1)H2  (1)
As discussed in Cortright, et al., this reaction may be carried out in the presence of a catalyst, for instance a nickel-based catalyst on a modified alumina support. Cortright et al. further report the use of subsequent water-gas shift reactions to create hydrogen gas from the carbon monoxide produced as a byproduct of the hydrocarbon reformation. Cortright, et al., U.S. Pat. No. 6,699,457, is incorporated by reference as if fully rewritten herein.
Hydrogen production from starch-derived products such as polyols (for example, sorbitol) or ethanol have also been proposed. For instance, Cortright, et al. report production of hydrogen by reforming of oxygenated hydrocarbon feedstock. The Cortright, et al. method purportedly includes reaction of water and a water-soluble oxygenated hydrocarbon (or hydrocarbons) having at least two carbon atoms in the presence of a catalyst containing a metal from the Group VII transition metals or their alloys.
The reaction proposed in Cortright et al. purportedly proceeds initially according to the following equation:CxH2yOx→nCO+yH2  (2)The carbon monoxide produced in that reaction is then subjected to the water-gas shift reaction:CO+H2O→CO2+H2  (3)In the steam reforming according to reaction equation (3) the steam is used in excess. The so-called “steam to carbon ratio” (S/C) is used to characterize the excess water that is used. Normally a value for S/C of between 1.2 and 2.0 is chosen. In the case of the reforming of methanol S/C is identical to the molar ratio of water to methanol. For use in fuel cells gas mixtures are required that have a low carbon monoxide content with a high hydrogen content, since carbon monoxide deactivates the anode catalyst at which the oxidation of the fuel takes place. Normally amounts of carbon monoxide in the fuel of below 100 ppm, preferably less than 10 ppm, are required. If the fuel is obtained by reforming methanol, this requirement can at the present time only be met by a subsequent purification of the reformate gas. The effort and expenditure involved are less the lower the carbon monoxide content in the reformate gas. For use in vehicles, for reasons of space and weight reforming catalysts are required that has a very high specific hydrogen productivity and a high selectivity, the selectivity of the formation of carbon dioxide being used to characterize the selectivity of the steam reforming. Cortright et al. reports the use of a number of starting materials for the oxygenated hydrocarbon process reported in the '457 patent, including “ethanediol, glycerol, sorbitol, glucose, and other water-soluble carbohydrates.” They claim that use of these starting materials allows them to perform their process at a lower temperature than other processes having an equivalent result.
Some hydrogen-production processes report the use of polyols as starting materials. To improve or enable polyol production, a number of catalysts have been suggested for hydrogenation and hydrogenolysis. These include, for example, ruthenium silica, cobalt-zinc based catalysts, and various metal catalysts such as alumina, nickel, platinum, palladium, and rhodium.
Other methods, apparatuses, and catalysts for hydrogen production are reported in the following publications, all of which are incorporated by reference herein. Wang, D. et al. “Production of Hydrogen from Biomass by Catalytic Steam Reforming of Fast Pyrolysis Oils” Energy & Fuels (1998) 12:19-24; Garcia, L. et al. “Catalytic Steam Gasification of Pine Sawdust. Effect of Catalyst Weight/Biomass Flow Rate and Steam/Biomass Ratios on Gas Production and Composition” Energy & Fuels (1999) 13:851-859; Wang, D. et al. “Biomass to Hydrogen via Fast Pyrolysis and Catalytic Steam Reforming of the Pyrolysis Oil or Its Fractions” Ind. Eng. Chem. Res. (1997) 36:1507-1518; Aznar, M. P. et al. “Improved Steam Gasification of Lignocellulosics Residues in ca Fluidized Bed with Commercial Steam Reforming Catalysts” Ind. Eng. Chem. Res. (1993) 32:1-10; Turn, S. et al. “An Experimental Investigation of Hydrogen Production From Biomass Gasification” Int. J. Hydrogen Energy (1998) 23:641-648; Rapagna, S. et al. “Catalytic Gasification of Biomass to Produce Hydrogen Rich Gas” Int. J. Hydrogen Research (1998) 23:551-557; Asadullah, M. et al. “Energy Efficient Production of Hydrogen and Syngas from Biomass: Development of Low-Temperature Catalytic Process for Cellulose Gasification” (2002) 36:4476-4481; Jacobsen, H. “Heterogeneous Chemistry: Catalysts for Hydrogen Production from Biomass” (2004) 43:1912-1914; Rapagna, S. et al. “Development of catalysts suitable for hydrogen or syn-gas production from biomass gasification” Biomass & Bioenergy (2002) 22:377-388; Garcia, L. et al. “Catalytic steam reforming of bio-oils for the production of hydrogen: effects of catalyst composition” Applied Catalysis A: General (2000) 201: 225-239; Chen, G. et al. “Catalytic pyrolysis of biomass for hydrogen rich fuel gas production” Energy Conversion and Management (2003) 44:2289-2296; Fatsikostas, A. N. et al. “Steam reforming of biomass-derived ethanol for the production of hydrogen for fuel cell applications” Chem. Commun. (2001) 851-852; French, R. et al. “Fluidizable catalysts for hydrogen production hydrogen; Hydrogen from steam biomass pyrolysis products” (2002) 47(2):759-760; Llorca, J. et al. “Effect of sodium addition on the performance of Co—ZnO-based catalysts for hydrogen production from bioethanol” Journal of Catalysis (2004) 222: 470-480; Breen, J. P. et al. “Metal-catalysed steam reforming of ethanol in the production of hydrogen for fuel cell applications” Applied Catalysis B; Environmental (2002) 39:65-74; Arndt, J-D. et al. “Continuous method for the production of sugar alcohols” WO 2004/052813 A1 (2004).
Although a number of processes and starting materials for production of hydrogen and/or syn gases have been suggested many involve use of starting materials that are expensive to produce, or that could more economically be used to produce other products. There remains a need in the art for more economic feedstreams for production of hydrogen.